Implementing Your Filter
The specifics of a transform filter will vary from application to application. The DirectShow Transform Filter Wizard creates stub code for a number of methods that you must implement to create the specific functionality for your filter. For a transform filter, the Transform, CheckInputType, CheckTransform, DecideBufferSize, GetMediaType, and CheckTransform methods must be reimplemented to meet the specific needs of your filter design. (Each of these methods and their functions are covered in Chapter 10.) For an in-place transform filter, the CheckInputType and CheckTransform methods must be reimplemented in your own filter designs. You will also want to implement the Transform method so that the filter actually does something interesting.